That's the final whistle - a huge ovation from the Griffin Park crowd for a cracking tie and a wonderful effort from Brentford, who led twice. So it's back to Stamford Bridge after a 2-2 draw.

90'

Seconds remaining, and a draw is the least Brentford deserve. They've been great, and an utter credit to League One. Donaldson blazes an effort over from an impossible angle, and that should pretty much be that for this game.

90'

Chelsea want a penalty as a cross hits Harlee Dean. The Blues say handball, the referee says no. You've seen them given, as the saying goes.

90'

It's too deep, and Turnbull claims that. At the other end, a deep ball towards Mata is just too deep and eludes him.

90'

Brentford have a free-kick for handball against Ramires midway inside the Chelsea half. A last chance for a Bees winner?

90'

Four minutes of added time as the flag goes up against Torres.

90'

Great play by Logan, who just will not give Ramires a second and blocks his attempt to swing a cross into the area.

90'

Into the last minute of normal time as the flag goes up against Donaldson.

89'

Brentford scramble the ball away after a purposeful run by Torres takes him into the Bees area.

88'

End to end again - a Mata cross finds Lampard, but his looping header is easily caught by home 'keeper Moore.

88'

The ball is played long towards Donaldson - too long, though, and Turnbull claims it on the edge of his box.

87'

Ba has a touch and Torres finds Lampard in space. He hits a trademark shot from the edge of the area, and Moore holds on at the second attempt.

86'

Forward come the Bees again. They win a throw, but then concede a free-kick, and Chelsea have the chance to launch another attack.

86'

Could have been one for Chelsea - Lampard almost finds Torres inside the area, but Dean is there with a crucial touch for Brentford.

85'

Five minutes remaining, and things are delicately poised here. Will there be a late winner for either side, or is it back to Stamford Bridge for a replay?

84'

Winger Sam Saunders is on for Adam Forshaw in Brentford's last change of the afternoon.

83'

GOAL: An out of nothing equaliser for Chelsea - the ball falls to Torres just inside the D, and he curls it beautifully into the corner past Moore. A wonderful finish from Torres, who had been one of his side's most anonymous players.

82'

And here comes Ba - Bertrand makes way.

81'

Bertrand has a great chance, but plants his header wide of the top corner. So nearly an equaliser - and it should have been.

81'

Lampard wins another corner for Chelsea, and Demba Ba is preparing to enter the fray for them.

80'

Into the final ten minutes of normal time - Chelsea's change saw a loud chorus of "you don't know what you're doing" hurled in the direction of Benitez by the Chelsea fans.

79'

Ivanovic off, Aspilicueta on for Chelsea, and penalty scorer Forrester off and Scott Barron on for Brentford.

79'

The ball is played up to Torres, who takes it on his chest before mishitting from the edge of the area.

78'

Cahill heads it across, and Terry can't quite get there. Brentford hammer it away, it's played back in and Moore claims as Ivanovic attempts an overhead.

77'

Chelsea have a corner. Time is ticking away for them here.

76'

"Champions of Europe, you're having a laugh," sing the home fans.

75'

Logan slides a ball forward down the left, but the flag is up against Donaldson.

75'

A long and aimless ball from Chelsea, which Moore is happy to watch behind his goal.

74'

League One Brentford are a little over 15 minutes away from knocking out Chelsea, the FA Cup holders.

74'

Turnbull was booked for his challenge on Adeyemi. And just as Chelsea were getting on top, they find themselves behind again.

73'

GOAL: Forrester slots it low into the corner, and Brentford are back in front. Great penalty from the youngster, placed beyond the 'keeper's reach.

73'

Forrester to take it...

72'

Donaldson plays Adeyemi through, and he tumbles over Turnbull.

71'

PENALTY TO BRENTFORD!

70'

Bees goalscorer Trotta comes off and midfielder Tom Adeyemi is on in his place.

69'

Forshaw has a go on the volley - it's blocked, and his follow-up sails high in to the Brook Road stand.

68'

Bertrand, at the other end, concedes a corner - from it, the Bees win another on the opposite side.

67'

...and Oscar can't get the ball back to him. There would have been danger for Brentford had he been able to.

66'

Bertrand raids forward for Chelsea. Mata takes over and gets the ball to Oscar on the edge of the area...

66'

Hodson floats it in, but it's too deep and goalkeeper Turnbull is there to claim for Chelsea.

65'

Free-kick to the Bees as Ramires clips Donaldson midway inside the Chelsea half.

64'

Forshaw and Logan link: the latter crosses and it's cleared. Hodson has a shot from outside the box, but it's blocked before it can travel too far.

63'

Cole crosses for the Blues again - he's been much more prominent in this half - and Diagouraga deals with it for Brentford.

62'

Trotta loses out in midfield: Chelsea, who were winning so few challenges before half-time, have certainly upped their game in that department.

61'

Can Brentford rediscover the zip they showed in the first period? They're being forced deeper as this half goes on.

60'

The ever-lively Forrester then tries to make a nuisance of himself on the edge of the Chelsea box, but he's crowded out.

59'

Chelsea win a corner, but there's some pushing and shoving in the Brentford area as that ball comes over, and it's a free-kick to the home side.

58'

A good challenge by Forshaw as Chelsea again look to build on the Brentford right.

57'

Trotta tries to get Brentford going, engineering a one-two with Douglas on the right, but it's cleared. Chelsea, suddenly, are in the ascendancy and having much more of the ball.

56'

That fires Chelsea - Cole crosses, the ball falls to Mata, but he doesn't connect properly and Moore is able to dive and save.

55'

GOAL: A brilliant moment from Oscar, wriggling past opponents, finding space in the area and rifling a superb finish high into the net. All square at Griffin Park.

54'

Donaldson is almost freed for Brentford, but the pass from Diagouraga is a touch too strong and Turnbull can get there.

53'

Good defending again from the hosts as Torres tries to make something happen. There's been a bit of an increase in Chelsea's tempo, as you would expect.

Turnbull slices his goal-kick, and Brentford come again through Donaldson. Lampard loses out and Forrester has a chance to shoot here...

41'

Forrster again harries Ivanovic on the Brentford left, and wins the ball. The Chelsea man is rather fortunate to be given a free-kick there.

40'

Five minutes or so to the break, and the besuited Rosler can be very proud of what Brentford have done so far.

39'

Ramires fouls Forrester. The hosts cross the ball deep, and again Chelsea don't look comfortable in clearing their lines.

37'

At the other end, Diagouraga crosses and Chelsea, squinting collectively into the sunshine, clear with some uncertainty.

36'

Diagouraga fouls Ramires in midfield - a bit of a juddering challenge, that one. Again, the visitors get the free-kick all wrong.

36'

Then Ivanovic crosses again and Craig clears for Brentford, who have defended well (when they've needed to).

35'

Ivanovic crosses dangerously and when it's cleared as far as Cahill he again sends an attempted pass straight off the pitch.

34'

Brentford, for once, give the ball away in a dangerous place but Lampard is crowded out and Dean gets it clear.

33'

No nonsense from Douglas there, hacking the ball out of the Brentford area. Many of the big-name visitors have been utterly anonymous so far.

32'

Gary Cahill gives the ball away, but Trotta is offside as he looks to get on the end of Forrester's pass.

31'

Seconds later, another Forrester run ends with a low shot that is dragged wide of Turnbull's near post.

30'

Logan down the left for Brentford. He rolls it across the box, but the effort on goal by Forshaw is wide.

29'

It's notable that, with almost half an hour to play, Chelsea have not had a clear-cut chance. The better openings have fallen to Brentford.

29'

Lampard's delivery is uncharacteristically poor, and that rather sums up Chelsea's afternoon so far.

28'

Ramires wins the ball and is fouled by Trotta halfway inside the Brentford half. Free-kick to Chelsea.

27'

Forrester looks the pick of the bunch for the Bees - great skill and great determination.

26'

He left Ivanovic trailing, but got his shot wrong and it bends harmlessly wide of the far post.

25'

Rosler will be delighted with the way his side have played in this first 25 minutes - they've been really good, showing no fear. Harry Forrester demonstrates that with a fine tackle and advances on the area...

24'

And there goes Trotta again: Ramires forced to hack the ball out for a throw this time.

23'

Forrester and Trotta link well down the left, but Cahill is adjudged to have been fouled.

22'

Another misplaced pass from Benitez's gang. They get it back, but Lampard can't find the right ball across the edge of the Brentford area.

21'

Oscar tries to do something about it, linking with Ivanovic. Logan shuts the door on that break, though.

21'

Then Marin misplaces a pass and Hodson steps in for Brentford. Chelsea are scrappy at the moment.

20'

Nearly a nasty moment for Brentford - the ball bobbles away from a defender, but the pass into their penalty area is claimed by Moore as Bertrand lurks.

19'

Forrester, not once but twice, wins the ball off more illustrious opponents in midfield.

18'

As if to emphasise that, Terry pays an utterly aimless ball down the left for Chelsea. The Bees fans enjoyed that one.

17'

Good skill by Donaldson, who is eventually crowded out after shuffling the ball away from a couple of defenders. Brentford on top.

17'

The kick is a poor one, however, and Chelsea get that away without either stress or strain.

16'

Corner for Brentford. Forshaw, again on that left, crosses low and it's scrambled behind.

16'

Great play by Forrester down the left. He breezes past Ivanovic, but his ball in is cleared for a throw.

15'

You can say, at the moment, that Brentford look the more constructive of these two sides on what is a bit of a bobbly pitch.

14'

Ramires hacks a clearance and Harlee Dean nearly finds Douglas, who is just unable to control in what would have been a dangerous position down the left.

13'

It is, but he gets too much elevation on his strike and it flies over the top.

12'

The referee is trying to make sure the wall is back far enough, and the ball will be tapped to Forrester for a strike.

12'

Real chance for the home side thanks to that aberration in the Chelsea box.

11'

Now then. Terry ushers the ball back to Turnbull, and he picks it up with Donaldson lurking. Indirect free-kick to Brentford, just inside the area.

10'

Trotta, wide on the left, advances on the Chelsea area but slices his shot into the Ealing Road stand behind the goal.

9'

They'll be pleased with this start, the Bees. Logan exemplifies their work, sliding in to win the ball.

8'

Ivanovic crosses, Brentford head clear and Oscar is unable to pick up the pieces on the edge of the box.

7'

Donaldson flicks, and Trotta harries 'keeper Turnbull, forcing him to slice the ball out of play. Good work by the Brentford man.

6'

Hodson does well, intercepting for Brentford as Chelsea threaten to build with some neat passing down their left.

5'

Donaldson, the Bees dangerman, hasn't really been able to get into the game yet. But as you would expect from this Rosler side, they are trying to be constructive with the ball whenever they get it. No aimless hoofing here.

4'

Keeper Moore was able to just watch that one wide. Forshaw tries a crossfield pass, which Chelsea cut out with some ease.

4'

Marin does well, moving on to Cahill's pass to find Oscar, who drags a low shot harmlessly wide of the far post.

3'

A dangerous Chelsea ball skids across the face of goal, and Brentford escape as it eludes Torres.

2'

Good passing from Brentford, but Ivanovic heads the ball away as they try to spring down the right.

2'

Bright and sunny conditions here in west London. Chelsea on the ball, and Brentford haven't really had much of a touch yet. They get one now, as Lampard puts the ball out of play for a throw.

1'

An early throw for the Blues, level with the edge of the Brentford penalty area. Torres can't quite get the flick, and the Bees get it away.

1'

Torres and Oscar are over the ball - and referee Moss blows his whistle to start proceedings.

Chelsea will get things under way in front of a packed house at this atmospheric London stadium (which has a pub on each corner, fact fans).

Rafa Benitez is striding across the pitch at Griffin Park - not really the sort of ground he's used to. It's a strong starting XI for Chelsea, but the Bees are playing well under the astute management of Uwe Rosler.

ESPN's Andrew Orsatti tweets: "I guess you can say there's a real buzz around Griffin Park as the Bees of Brentford try to sting Chelsea in the FA Cup. No pun(s) intended."